1. Field of the Invention
The present invention pertains to the field of connectors for transmitting signals between circuit boards or other components. More particularly, the present invention pertains to the use of a coaxial connector arrangement for connecting such circuit boards or other components.
2. Description of Related Art
Improving the overall signal transfer characteristics of circuit board connectors can allow higher frequency signals to be transferred through such connectors. As a result, system level signal frequencies may be raised when an improved connector is employed in a system where the connector would otherwise limit the speed of system communication.
Stackable connectors are connectors which allow circuit boards that are substantially parallel to be connected. Using prior art techniques, high-frequency signals that must pass from one circuit board to another arc electrically connected using an ordinary interconnect pin/socket set. These prior art pin/socket sets typically include a pin mounted on a first circuit board and electrically coupled to a first signal line on the first circuit board. A socket mounted on a second circuit board which engages the pin couples the first signal line to a second signal line in the second circuit board.
Adjacent pin/socket sets and any intervening gaps or insulating material define noise immunity and impedance characteristics for such prior art pins. In some cases, these adjacent pin/socket sets may be used as barrier posts (which may be biased to a specific potential) in an attempt to achieve the desired impedance and/or noise immunity. In some cases, despite the use of pin/socket sets as discrete barrier posts, due to unequal spacing and gaps, electrical noise may pass between the barrier posts and induce spurious currents in the signal pin. Thus, while this prior art arrangement provides a degree of noise immunity, the impedance control and noise immunity characteristics may no longer suffice as the frequency of signals passing through such connectors continues to rise.
Additionally, the prior art provides no simple and effective means of controlling the characteristic impedance of the signal pin. Impedance is determined by the spacing between pin/socket sets on the connector, in together with the performance characteristics of the dielectric material occupying the space between the signal-pin/socket set and adjacent pin/socket sets. Adjustment of either of those parameters may be difficult to achieve. Spacing the surrounding pins close enough to achieve the desired impedance control would likely result in fabrication and/or usability difficulties. Changing the dielectric material for the high-speed circuits would likely require change for the entire connector, necessitating reconsideration of mechanical stability and other issues.
Thus, the prior art fails to provide a connector which provides adequate noise immunity and sufficiently controllable impedance characteristics. A connector that does provide noise and/or impedance control could be advantageous in propagating high frequency signals between stacked circuit boards or other parallel surfaces.